This invention pertains to a wear-resistant tool insert for machines used in the production of nails, screws, rivets, and similar objects starting with wire material.
Nails are produced by feeding wire to a clamping punch and cutter. The clamping jaws hold the wire stock in position while the cutter shapes the nail point and the punch shapes the nailhead. Currently, nail-manufacturing machines having reciprocating clamping jaws can produce approximately 600 nails a minute. Nail machines, as in prior art designs, include grippers/clamping jaws and cutters that were made from conventional steel U.S. Pat. No. 5,195,931.
More recently, clamping jaws have been made to include inserts made from hard wear-resistant material, such as cemented tungsten carbide as shown in U.S. Pat. No. 5,979,216.
Wear-resistant tool inserts of this type are employed in pairs in nail manufacturing machines and are called impact or clamping jaws and pincer jaws. The clamping jaws are often used as replaceable parts in toolholders. The clamping jaws have elongated, prism-like trapezoidal cross-section base elements corresponding to similar recesses in the toolholders. One working surface of the clamping jaws has one or more clamping grooves for tightly clamping the supplied wire and also a recess for forming the desired head shape of the object to be produced. The clamping jaws are arranged in the machine so that the clamping grooves are located opposite each other. In the course of the machine operation, the clamping jaws are closed or opened. In the closed state, the supplied wire is tightly clamped in the clamping grooves. In the clamped state, the head of the nail, screw or rivet is formed. For better clamping of the supplied wire, the clamping grooves are preferably transverse and semicircular in form.
After completion of the head, the nail point is elongated by closing two opposing pincer jaws. The pincer jaws are clamped tightly in machine toolholders or attached directly in the machine. The pincer jaws have a symmetrical profile with several cuts where the end of the finished point is shaped and the point is elongated.
A prior art damper jaw body with a hard material insert is depicted in European Patent 401,918 B1 by Michael Schratter which was filed on Jun. 5, 1990. The clamping insert wire holding groove 5, as shown in the drawings, has a plurality of serrations for better clasping the wire. As can best be seen in FIG. 1 of the European patent, a screw 4 is employed to clamp the insert 2 to the clamp jaw body.
The tool inserts are often manufactured of hard metal to reduce wear. If the wear on the clamping grooves or on the cutters is excessive, then the inserts must be replaced. Replacement of hard material inserts requires downtime, increasing equipment costs, and reduces profits.
It is, therefore, an object of this invention to address the problem of creating wear-resistant tool inserts for machines for the manufacture of nails, screws, rivets, and such.
It is another object of this invention that hard metal is used as a particularly favorable material for the tool insertsxe2x80x94the hardness being of at least 1,500 (HV30)xe2x80x94as measured in a Vickers test.
The invention introduces a new groove design having a smooth wave that reduces the wear rate of the groove improving the life expectancy of the hard material clamping insert.
Another object of the invention is to design a clamping jaw that is easily accessible for permitting replacement and/or indexing of the carbide-clamping insert.
This invention is further described in reference to the figures. It will be understood by those of ordinary skill that the embodiments described and illustrated serve as examples of this invention and that other embodiments will similarly accomplish the same objectives. Though not specifically illustrated or described in this specification, it is further intended and understood that all other embodiments, accomplishing the same objectives, are intended to be covered and claimed in this application.